by Emily Sohn
Hakai, May 3, 2016
I’ve been meaning to get this pitch together for months and finally got a little breathing space to sketch it out. Here’s the idea:
Every year in tropical ocean waters from Florida to the Philippines, fish collectors snag angelfish, blue tangs, clownfish, damselfish and other species by the millions to stock pet stores and aquariums. And while demand for tropical fish remains high, problems are brewing beneath the surface of the world’s oceans that threaten the multi-million dollar trade in all sorts of ways. That list includes unsustainable fisheries in places like Indonesia, where over-harvesting and damaging collection practices are destroying reefs and depleting fish stocks. Even in Hawaii, where data show that fish collecting is sustainable and populations are thriving, a fierce campaign to ban the taking of fish from the state’s reefs has escalated to the point of underwater fights between disagreeing SCUBA divers.
As those battles play out, scientists are looking for a solution not out at sea but in their labs, where they are trying to breed tropical marine fish in captivity. Progress has been incremental: so far, researchers have cracked the code of about 50 species of marine fish that they can now farm in tanks, says Craig Watson, director of the University of Florida’s Tropical Aquaculture Laboratory. That’s a tiny portion of the 1,800 species sold on the international market. “While we’ve had some minor successes,” Watson says, “we haven’t had the home run we’ve been trying for.”
Watson’s team is one of several that are gunning to unlock the secrets of tropical fish breeding (freshwater fish are easier to cultivate), but challenges abound. Among them, many marine fish produce microscopic eggs that float to the surface before hatching into miniscule, often transparent larvae that have proven extremely difficult to feed. A graduate student in Watson’s lab spends most of his time developing live food for fish larvae and experimenting to see what will work best. Other researchers are experimenting with probiotics, light intensity, turbidity and more.
Tangs, which are by far the most popular aquarium fish, are among the “holy grail” species that scientists are working hardest to propagate. And while several teams have reported encouraging results, success remains elusive. Last year, a collaborative research group called Rising Tide reported an 83-day survival record for yellow tang larvae, an exciting achievement that nobody has come close to replicating since.
Would Hakai be interested in a story about efforts to breed tropical marine fish? The narrative could follow Watson’s group (or another team, depending on who pans out to be the most compelling characters) as they carefully regulate conditions in laboratory tanks and then hold their breaths while assessing whether their efforts are making any progress. Along the way, we could explore debates about the mostly unregulated ornamental fish industry, the clash between the public’s desire for colorful fish and the environmental impacts that often ensue, and the potential for science to calm the waters. The ongoing legislative battles in Hawaii are adding urgency to the drive for better success rates.
Sources would include Watson’s group at the University of Florida, as well as Judy St. Leger, director of Rising Tide Conservation, which is funded by SeaWorld, PetCo and other groups. I’d also want to talk with researchers involved in marine aquaculture programs at other institutions and private companies, including one at the University of Hawaii, another at the University of Texas, Austin. I believe the Disney aquarium is also involved in the breeding game. I’ve already talked with multiple experts in Hawaii about the raging battle over the state’s fish stocks and could follow up with them again.
Let me know if you have interest or any questions. Thanks!